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John D. Wrbanek, Gustave C. Fralick, and Susan Y. Wrbanek Glenn Research Center, Cleveland, Ohio

Development of Techniques to InvestigateSonoluminescence as a Source of

Energy Harvesting

NASA/TM—2007-214982

October 2007

AIAA–2007–559

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Glenn Research Center

Cleveland, Ohio 44135

Prepared for the

43rd Joint Propulsion Conference

sponsored by the American Institute of Aeronautics and Astronautics

Cincinnati, Ohio, July 8–11, 2007

AIAA–2007–559

John D. Wrbanek, Gustave C. Fralick, and Susan Y. Wrbanek Glenn Research Center, Cleveland, Ohio

Development of Techniques to InvestigateSonoluminescence as a Source of

Energy Harvesting

NASA/TM—2007-214982

October 2007

8/14/2019 Nasa/Tm—2007 214982


Acknowledgments

This work was sponsored by the Alternate Fuel Foundation Technologies Subproject of the Low Emissions Alternative Power Project and the Breakthrough Propulsion Physics Project at the NASA Glenn Research Center. The authors would like to thank

Nancy Rabel Hall of the Fluid Physics and Transport Branch at Glenn Research Center, the project scientist of the “Buoyancy

Driven Instabilities in Single Bubble Sonoluminescence” experiment, for providing references and information on

sonoluminescence and for reviewing this report. We would also like to thank Kenneth Weiland (retired) and James Williams of

the R&D Labs Technical Branch for their optical hardware and electronics support in this effort, and Drago Androjna of Sierra

Lobo, Inc. as part of the NASA GRC Test Facilities Operation, Maintenance, and Engineering (TFOME) organization for

SEM/EDAX support. Finally, we are thankful to Jonathan Wright of University of Florida for his help in reviewing this work.

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This report is a formal draft or working

paper, intended to solicit comments and

ideas from a technical peer group.

This report contains preliminary findings,

subject to revision as analysis proceeds.

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NASA/TM—2007-214982 1

Development of Techniques to Investigate Sonoluminescence as a

Source of Energy Harvesting

John D. Wrbanek, Gustave C. Fralick, and Susan Y. Wrbanek

National Aeronautics and Space Administration

Glenn Research Center Cleveland, Ohio 44135

Abstract

Instrumentation techniques are being developed at NASA Glenn Research Center to measure optical,

radiation, and thermal properties of the phenomena of sonoluminescence, the light generated using

acoustic cavitation. Initial efforts have been directed to the generation of the effect and the imaging of theglow in water and solvents. Several images have been produced of the effect showing the location within

containers, without the additions of light enhancers to the liquid. Evidence of high energy generation in

the modification of thin films from sonoluminescence in heavy water was seen that was not seen in light

water. Bright, localized sonoluminescence was generated using glycerin for possible applications to

energy harvesting. Issues to be resolved for an energy harvesting concept will be addressed.

Introduction

Sonoluminescence has risen to be a source of interest to those outside of the ultrasonic community

over the last decade (ref. 1). The processes of understanding the effect lead to the challenge of utilizing

some of its more interesting properties in practical applications.

The sonoluminescence phenomena is defined as the generation of light from sound waves, firstdiscovered in the 1930s as a by-product of early work on sonar (ref. 2). The report in 1992 of the

ultrasonic trapping of a single glowing bubble in a flask of water generated a cascade of research (ref. 3).

The glow from the bubble was found to be generated in bubbles compressed to at least 150 kPa in an

extremely short duration flash (<12 psec), and had temperatures of at least 25,000 K for the single bubble

(refs. 4 and 5). Bubbles of noble gases were seen to flash brighter, but the nature of the liquid was alsoseen as playing a large role in the flashes as well (refs. 6 to 8).

Shortly after research results on trapped single bubbles were published, models were developed to

explain these measurements. Simple shock calculations showed that peak temperatures inside the

sonoluminescent bubbles could reach 3×108 K based on the collapse of an ideal spherical gas bubble

(ref. 9). Assuming a non-spherical collapse, the high speed jet striking the opposite side of the bubble

gave rise to the possibility of the water being fractured on the molecular scale and generating light as

fracto-luminescence (refs. 10 and 11). The extremely rapid collapse of the bubble led to the theoretical

examination of sonoluminescence as an effect of quantum vacuum radiation (ref. 12). The lack of an

after-glow suggested a cooperative optical emission, like that of an optical laser or superradiance (refs. 13

and 14). The actual process may be a combination of any of the above (refs. 15 to 18). A simplified

schematic of the current model of the process is shown in figure 1 (after ref. 1).

Initial examination of the phenomenon by the National Aeronautics and Space Administration(NASA) involved sponsoring measurements of single-bubble sonoluminescence in microgravity (0g

vertical acceleration) and hypergravity (2g vertical acceleration) performed on a KC-135 parabolic

research flight by the University of Washington. The researchers discovered that light emission

brightened promptly by 20 percent and increased continually under microgravity, suggesting buoyancy-

driven instabilities are a critical limitation to the effect (ref. 19). Flight hardware for an ensuing

experiment on ISS was under development in 2003 (shown in fig. 2), but was cancelled following a

redirection in NASA’s space exploration efforts.

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NASA/TM—2007-214982 2

Even as these theories are being explored, applications for the effect are taking shape, from fusion

containment (refs. 10 and 20 to 22) to thin film deposition systems (ref. 23). Recently, Purdue Universityresearchers at Oak Ridge National Laboratory claimed to have demonstrated thermonuclear fusion using

sonoluminescence in deuterated acetone (refs. 24 to 28).

If realized, harnessing the high energy release in safe, emission-free ultrasonic processes would lead

to the development of revolutionary power systems for in-flight use for both aircraft and spacecraft. The

benefits of an on-board fusion power system will be in the reduced fuel consumption, lower emissions

and reduced noise for many types of aircraft. A practical fusion power source would replace the

conventional gas turbine auxiliary power units and electrical generators in aircraft, and fuel cells and

batteries in spacecraft, improving flight and mission capability. Longer-term use of the power source

will have both an environmental benefit and act as a positive contributor to the country’s energy

diversification, as well as enable new missions for both air and space.

NASA Glenn Research Center (GRC) is developing instrumentation technologies for the support of

the mission to pioneer the future in space exploration, scientific discovery, and aeronautics research.These technologies also enable the capabilities for long duration, more distant human and robotic

missions for the Vision for Space Exploration.

As part of our mission to conduct basic and applied research on advanced instrumentation

technologies, GRC has begun an examination of sonoluminescence for instrumentation and measurement

technique development. The objective of the effort is to investigate claims and theories of power

generation based on sonoluminescence. The approach will initially determine whether there is any

difference in the emission from bubbles in light water and heavy water then other solvents. Eventually

conclusions on sonoluminescence-based power generation concepts will be formulated utilizing the data

from our experiments. In this paper, we report on progress made to date on our investigation of the

phenomena of sonoluminescence in terms of its generation and imaging.

ApparatusThe basic equipment for sonoluminescence consists of a flask containing the liquid, ultrasonic

transducers, a piezoceramic amplifier and a function generator (ref. 4). Schematics of our test apparatus

are shown in figures 3 and 4. The transducers are driven by an amplified signal from the function

generator to saturate the fluid with ultrasonic waves. The voltage and current flowing across the

transducers can be monitored, and instrumentation (such as a microphone, spectrometer and a

photomultiplier tube) can be positioned to monitor the resulting sonoluminescence.

Figure 2.—Sonoluminescence flight hardwaretesting in 2003.

Figure 1.—A schematic of the sonoluminescenceprocess (after ref. 1).

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NASA/TM—2007-214982 3

If the ultrasonic energy from the transducers can be concentrated into a small enough uniform spot,

and the liquid does not contain a large amount of dissolved gas, the liquid can be ruptured in cavitation

that is controlled. The cavitation can cause a single glowing bubble to appear that is reasonably stable,

known as single-bubble sonoluminescence (SBSL) (ref. 4). If the liquid is nearly saturated with dissolved

gas, the cavitation forms filamentary patterns that are chaotic as the input energy is distributed throughout

the flask. A cloud of glowing bubbles can result, which is referred to as multi-bubble sonoluminescence

(MBSL) (ref. 29). Either way, the sonoluminescence is located at or near regions of maximum pressure

(ref. 29).

Imaging

The initial apparatus for our tests was a resonating test apparatus as shown in figure 3, consisting of a

250 ml round borosilicate glass flask with a pair of piezoceramics attached with epoxy on opposite sides

and filled with refrigerated (~17 °C) distilled water. Patterns of MBSL were produced at various

frequencies. Although most of the patterns were chaotic, two stable geometric patterns were reproducible.

The patterns of interest were rings having four and eight nodules at 68.5 and 93.0 kHz, respectively. The

MBSL patterns were faint, requiring the observers 20 min of dark adaptation in the lab to see them. To

determine the placement of fiber optic instrumentation for future investigations, the position of the MBSL

in relation to the sides of the flask needed to be recorded.

A low lux astronomical video camera was purchased to image the patterns. The camera was set to

maximum sensitivity and images were recorded using a 2-sec-frame integration setting. Images were

recorded with and without the frequency generator on, and with and without room lights on. The resulting

compilation of these is seen in figure 5. Only three of the nodules of the four-nodule ring are seen in the

image. The eight-nodule ring was too faint to be resolved by this method.

To help increase visibility of the MBSL, a sonoluminescence setup using a high power Sonicator

(ultrasonic liquid processor and cell disrupter, Misonix, Inc.) test apparatus as shown in figure 4. The test

cell used initially were a 100 ml borosilicate glass beaker filled with refrigerated distilled water, but later

a 50 ml quartz flask was used. Each used a titanium high intensity ultrasonic transducer horn probe in line

with the signal generator and amplifier instead of piezoceramics. As seen in figure 4, the transducer horn

was inserted into the open top of the beaker and flask. Besides capable of delivering high acoustic power,

the Sonicator test apparatus has the added benefit that the transducer is not physically attached to the test

cell as in the resonating test apparatus.

Figure 3.—Resonating test apparatus andassociated equipment.

Function

Generator

Amplifier

Trigger Voltage Oscilloscope

Signal Current

PZT PZT

Microphone

100x High Voltage

Probe 1 Ohm

Resistor

Flask

Spectrometer Photodetector

Quartz

OpticalFiber

Sonoluminescence

Neutron Detector

ScintillatorFiber

Flask

Function

Generator Amplifier Sonicator Horn

Sonoluminescence

Spectrometer Photodetector Quartz

Op t i cal

Fiber

Photodetector Light Output Monitor

Neutron Detector

Sonicator Transducer

ScintillatorFiber

Figure 4.—Sonicator test apparatus and associatedequipment.

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NASA/TM—2007-214982 4

With the resonating test apparatus, the previously reported (ref. 10) effect was observed of brighter

sonoluminescence glow in cooler water at the same driving voltage. In order to keep the water

temperature cool and the cells stable, a Peltier cooler box was modified from a commercial kit and

aluminum support rings were machined for use with the Sonicator test apparatus. The MBSL patterns

were generated in the both beaker and quartz flask cells with and without support rings by this method.

However, the patterns were not as defined as in the 250 ml flask, and the video camera was not able to

detect the patterns as well as the ring patterns with the resonating test apparatus.A 16-bit-grayscale CCD imaging system for terrestrial still deep-space astrophotography was

purchased to image the MBSL. Unlike the compiled image of figure 5 from three separate images, only

brightness and contrast level enhancement and the application of a noise filter was needed to achieve the

images shown in figures 6 to 10. The MBSL filament feature on the bottom of the flask in figure 6(b) is

approximately 25 mm wide by 1 mm thick, making the resolution approximately 100 µm/pixel. Thefilament structure is revealed with a gradient map on the edges of sonoluminescence intensity as false

color in figures 7(b) to 10(b).

The sonoluminescence filaments seen in figures 7 and 8 follow a conical pattern from the horn to the

base of the beaker and flask. The filament pattern has been reported elsewhere (ref. 29), but in our

images, the container is clearly visible, and no brightening agent was introduced into the water. The 50 ml

flask produced the brightest MBSL shown in figure 8, possibly due to the small volume and thus

increased concentration of the applied ultrasonic power.

The CCD imaging system was turned on the rings formed by the resonating test apparatus using the

250 ml flask, which had been at room temperature for several months. The ring patterns were reproduced,

as shown in figures 9 and 10, but dimmer and at higher frequencies than in figure 5 due to the room

temperature water. The rings in the images are smeared due the variation of the nodules positions about

the pressure maximums. The images reveal the rings as a “wavy” ring, with nodules near the piezoceramics.

The nodules of the eight-nodule ring are revealed as pairs of nodules shifting about the four

maximums of the four-nodule ring (only six of the eight nodules are visible in figure 10). In addition, in

comparing figures 9 and 10, the four-nodule ring forms in the center of the flask, but the eight-nodule ring

forms slightly lower. The shift in position is not apparent to the dark-adapted observer since the flask is

not clearly visible in the darkened lab. Thus, this ability to image the flask and the sonoluminescence

effect together is demonstrated to be necessary if any precision is desired for the placement of in situ

instrumentation.

Figure 5.—Enhanced false-color image taken from video

of a ring of MBSL. The arrows indicate the three visible

nodules.

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NASA/TM—2007-214982 5

Figure 8.—Enhanced images of MBSL at 106.5 kHz in the 50 ml flask. Exposure time was 3 min

at f/2.8. The field of view is 7.1 by 5.4 cm. Image shown in (a) grayscale and (b) false color

highlighting filament structure with guides to outline the conical pattern.

(a) (b)

(a) (b)

Figure 6.—The bottom of a 100 ml beaker with the transducer horn (a) off and (b) on. The

MBSL filament appears centered at the bottom of the beaker (arrow). Both pictures are

1-min exposures at f/1.2.

(a) MBSL Off (b) MBSL On

Figure 7.—Enhanced image of MBSL at 108.8 kHz in the 100 ml beaker. Exposure time was

2 min at f/2.8. The field of view is 6.6 by 5.1 cm. Image shown in (a) grayscale and (b) falsecolor highlighting filament structure with guides to outline the conical pattern.

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NASA/TM—2007-214982 6

(a) (b)

(a) (b)

Figure 11.—True-color picture of sonoluminescence in light water (contrast-enhanced). Exposure time was 2 min. at f/2.8.

Figure 9.—Enhanced images of MBSL at 68.76 kHz in the 250 ml flask. Exposure time was 3 min

at f/2.8. The field of view is 11.4 by 8.8 cm. Image shown in (a) grayscale and (b) false color

highlighting filament structure with a guide to outline the ring pattern.

Figure 10.—Enhanced images of MBSL at 93.28 kHz in the 250 ml flask. Exposure time was

5 min. at f/2.8. The field of view is 11.4 by 8.8 cm. MBSL shown in (a) grayscale and (b) falsecolor highlighting filament structure with a guide to outline the ring pattern.

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NASA/TM—2007-214982 8

In expectation for miniature instrumentation applications, the three new samples first patterned a

1-µm-thick sputter-deposited platinum (Pt) resistance temperature detector and annealed at 1000 °C for

8 hr. The samples were then over-coated with a 3 µm layer of palladium alloy with 13 percent chromium

(PdCr). The PdCr alloy film is typically used as a strain gauge in high temperature environments. For

this instance, the alloy was used due to the affinity of palladium to hydrogen to allow the attraction

sonoluminescence (which supposedly contains hydrogen ions (ref. 31)) and the high adhesion strength of

the chromium to the oxide substrate. Though the Pt itself has some limited affinity to hydrogen, the filmdoes not adhere well to alumina at high temperatures, and failures of the Pt film were seen prior to PdCr

deposition after annealing.One of the new samples was exposed to MBSL in light water and another to MBSL in heavy water.

Under SEM, the sample exposed to MBSL in light water showed no significant modification of the film.

The sample exposed to MBSL in heavy water showed 4- to 5-µm-diameter craters in the PdCr film over-

coating the Pt film under SEM. As the Pt film was already failing, the third sample was exposed to MBSL

in both light water and heavy water. Images of the exposures are shown in figure 13 showing that thesample was exposed to sonoluminescence directly at the tip of the Sonicator horn. Again, the sample

exposed to light water showed no modification of the film, but after the heavy water MBSL exposure, the

4- to 5-µm-diameter craters in the film were apparent under SEM. No craters in the PdCr film directly

deposited on the alumina substrate were seen. Figure 14 gives a side-by-side comparison of the film at

different magnifications after the light water exposure and after the heavy water exposure.Table I gives a summary of some properties of the materials used in the samples (refs. 32 and 33).

Delaminating of films is considered a zero order affect of mismatches between the two materials

Coefficient of Thermal Expansion (CTE). The grain failures are seen in the film with PdCr on Pt and not

the PdCr suggests that the expansion of the PdCr on Pt is greater than that of the PdCr compared to

alumina. However, table I indicates that the adhering PdCr has a greater CTE mismatch to the alumina

substrate than the Pt film that was delaminating.

TABLE I.—SAMPLE SUBSTRATE AND FILM PROPERTIES (REFS. 32 AND 33) Material Density,

g/cm3 Melting point,

K

Heat of fusion,

J/g

Specific heat,J/gK

Thermalconductivity,

W/mK

Thermaldiffusivity,

mm2/s

Coefficientof thermalexpansion,

(CTE)(10 –6/°C)

Heat of oxideformation,

kJ/mol

Al2O3 3.92 2300 16,435 0.880 30.0 8.70 8 -----

Pt 21.5 2141 113.6 0.113 71.6 29.5 10 –173

Pd – 13%Cr 11.39 >1828 189.4 0.271 71.8 23.3 15 –468

Figure 13.—Film sample on Sonicator horn tip (arrows) exposed to SL in (a) H2O and (b) D2O at56kHz in 100 ml beakers.

(a) MBSL in H2O (b) MBSL in D2O

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NASA/TM—2007-214982 9

(a) From MBSL in H2O, 260× Magnification (b) From MBSL in D2O, 275× Magnification

(c) From MBSL in H2O, 2000× Magnification (d) From MBSL in D2O, 2000× Magnification

(e) From MBSL in H2O, 5000× Magnification (f) From MBSL in D2O, 5000× Magnification

Figure 14.—Surface of the 3-µm-thick PdCr films on 1-µm-thick Pt patterns seen by SEM under increasing magnification. The black surface at the bottom of the craters is non-conducting alumina.The films on the left (a, c, and e) were exposed to MBSL in H2O, and on the right (b, d, and f) to MBSLin D 0.

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NASA/TM—2007-214982 10

A first order estimate of the relative adhesion strength of films on oxides is the energy involved in

forming an oxide of the film (or heat of oxide formation). Table I shows that the PdCr alloy film has a

more negative heat of oxide formation, and thus more favorable to adhesion on the alumina than

platinum. The energy imparted to the film at the sonoluminescence point locations could be enough to

vaporize or melt the film when not adhering to the substrate but not enough to vaporize or melt the film

when it is adhering to the substrate.

The adhesion of the film to the substrate may be allowing the substrate to absorb the energy via

phonon vibrations, and the delaminating film does not allow the energy to be transferred directly into the bulk substrate material. Alternatively, the loose islands may have heated up and “popped” off due to

thermal expansion. This effect was seen on two separate samples in the heavy water runs and not seen in

the light water runs. The craters did not occur in the as-deposited Pt films in either light or heavy water.

Some failures of the PdCr film that did not involve failure of the Pt film were observed after exposure

to heavy water. The SEM image of the largest volume (14 by 8 by 3 µm3) is shown in figure 15. Analysis

by EDX of the failure area indicates that remnants of the PdCr film remain at the exposed Pt surface,

presumably in the form of several 0.375 µm radius globules observed in the SEM image. From table I,

at least 6.9 kJ/cm3 (or 605 J/g) (from table I) is required to melt PdCr from 20 °C, and 7.1 kJ/cm3 (or

332 J/g) for platinum. The craters and the PdCr film damage may be due to the same heating process of

the PdCr film. The lack of damage induced in the Pt film suggests the heating is not directly from

excessively high energy density of the MBSL in heavy water as compared to light water.

The primary result of these tests revealed that modification of PdCr films was observed by MBSLgenerated in heavy water but not light water. The film modification indicates high energy densities are

generated, though not high enough to indicate net energy generation by the MBSL itself. No effect was

observed on platinum films in heavy or light water.

Figure 15.—A large 20 by 10 µm failure of the PdCr film

over Pt film. Globules of PdCr are seen (arrows) on the1-µm-thick Pt film that is still adhering.

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NASA/TM—2007-214982 11

Sonoluminescence in Solvents

Previous studies of sonoluminescence brightness in various solvents give empirical relationships of

the brightness varying with the liquid’s viscosity, surface tension, inverse of the vapor pressure or a

combination of these properties (ref. 31). Properties of several solvents are reported in table II that have

been identified as producing some form of sonoluminescence (ref. 30 and 31). The stability of the

sonoluminescence light output with temperature is also reported to be dependent on the molar heat of vaporization of the liquid divided by the boiling point. Table II shows that the brighter sonoluminescence

should be seen in the solvents with higher boiling points (>100 °C), however a higher boiling point also

indicates a greater sensitivity to temperature.

From the information in table II, pure glycerin appears to be the best solvent for use in

sonoluminescence studies. Like the other higher boiling point solvents, glycerin is notoriously

hydroscopic, eventually absorbing water from the ambient air to stabilize as the 80 percent glycerin to

20 percent water mixture listed in table II. As glycerin is relatively safe and more readily available than

the other solvents, GRC began sonoluminescence studies using glycerin. Note that acetone and other low

boiling point solvents being explored elsewhere (refs. 24, 26, and 28) were rejected based on low

viscosity and high vapor pressure properties that are considered detrimental to sonoluminescence

intensity.

A cloud of cavitation was generated with a Sonicator setup (fig. 4) that corresponded tosonoluminescence in the liquid as seen under dark conditions, as shown in figure 16. The cavitation was

particularly localized, allowing for a promising target for the spectroscopy and radiation studies that are

planned.

TABLE II.—PROPERTIES IMPORTANT TO SONOLUMINESCENCE FOR DIFFERENT SOLVENTS AT 20 °C (REF. 30)

Solvent Boiling

point,

°C

Density,

ρ

(g/cm³)

Mol.

wt.

(g/mole)

Viscosity,

µ

(cP)

Surface

tension,

γ

(dynes/cm)

Vapor

pressure,

Pv

(Torr)

Molar

heat of

vaporization,

ΔHv

(kJ/mole)

Calculated

MBSL

intensity

( γ2/Pv

relative

to water)

Intensity

stability

with

temperature,

dI/(IdT)

(°C –1

)

Methanol 64.7 0.415 32.04 0.597 22.6 93.3 35.2 0.0180 –0.072

Ethanol 78.5 0.789 46.07 1.2 22.8 44 39.3 0.0386 –0.078

Acetone 56.5 0.792 58.08 0.326 23.7 186 30.3 0.0099 –0.064

Cyclohexane 81.4 0.779 84.16 1.02 25.5 84.8 29.9 0.0251 –0.059

Carbontetrachloride

76.8 1.595 153.84 0.969 27.0 91.3 29.9 0.0261 –0.059

Benzene 80.1 0.879 78.11 0.652 28.9 74.3 30.8 0.0369 –0.060

Light water 100.0 1.00 18.02 1.00 73.1 17.5 40.7 1 –0.076

Heavy water 101.4 1.11 20.03 1.25 73.1 16.6 42.1 1.13 –0.078

80%glycerin +20% water

121 1.209 77.28 60.1 66.6 3.5 85.7 4.16 –0.151

Ethyleneglycol

197 1.116 62.07 19.9 47.7 0.08 49.6 93.3 –0.073

Sulfuric acid 290 1.788 184.15 25.4 55.1 6.00E-05 94.1 166000 –0.116

Glycerin 290 1.261 92.09 1490 63.4 0.001 87.9 13200 –0.108

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NASA/TM—2007-214982 12

TABLE III.—ENERGIES OF REACTIONS OF INTEREST

Reaction Product Rest mass,

MeV/c2

(D = 1875.6128 MeV/c2)

Kinetic energy,

keV

D(d,n)3He

3Hen

2808.3914939.5536

8222458

D(d,p)T T p

2807.9027938.2720

12653786

D(d, γ)4He4He

γ

3727.3792-------------

75.723,771

Radiation Detection

There have been several claims of fusion reactions occurring in sonoluminescence (refs. 20, 21, 24,

and 26). The reactions cited are those that fuse two deuterium atoms to form (1) helium-3 and a neutron

(D(d,n)3He), (2) tritium and a proton (D(d,p)T), or (3) helium-4 and a gamma ray (D(d, γ)4He). These

reactions either can occur in a sonoluminescent bubble alone or interacting with a palladium catalyst

(Pd:D(d,b)Y reactions). See table III for the calculated energies of the products of these reactions.

The detection of the fusion reactions in the sonoluminescence test cells is made difficult by the nature

of the liquids used to generate the reactions. The low level ionizing radiation levels are difficult to detect

through water and heavy water due to their nuclear properties. The liquids can be analyzed for tritium

production or the detection of helium-3 and helium-4 out-gassing during the tests, but background

impurities and the diffusive nature of the gases makes such analysis slow and difficult. However, some

success have been reported using liquid scintillators and track detectors (ref. 28).A direct method to verify the reaction processes is by sampling the ionizing radiation in situ with

scintillation detectors. A thin film coated scintillating detector is under development to identify fusion

reactions occurring in sonoluminescence. The detector consists of a coated scintillating cube or fiber, a

waveshifting optical fiber, a fiber optic connector, and a photomultiplier (PMT) module. A schematic is

shown in figure 17.

Figure 16.—Cavitation in Glycerin with (a) room lights on, and (b) room lightsoff (contrast enhanced) showing localized sonoluminescence in a 40 mlcontainer. The Sonicator transducer was set to 56 kHz.

(a) Room Lights On (b) Room Lights Off

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NASA/TM—2007-214982 13

TABLE IV.—NUCLEAR PROPERTIES OF SCINTILLATOR AND COATINGS (REFS. 34 AND 35)

Material Density,g/cm3

Atomicmass,amu

Thermalneutron

absorptioncross

section, barns

76 keValpha

particlerange,

µm

3.75 MeV protonrange,

µm

2.5 MeVelectronrange,mm

Scintillator 1.032 6.25 0.35 0.7914 208.6 12.34

Rh 12.41 102.91 144.8 0.2724 42.34 1.480

Cu 8.96 63.546 3.78 0.2076 48.68 1.953

Pd 12.02 106.4 6.9 0.1797 44.83 1.552

The polyvinyltoluene (PVT)-based scintillator (Bicron BC–408 (Saint-Gobain Ceramics & Plastics,

Inc. for their inorganic and organic scintillators)) was used in the prototype detector design, generates a

pulse of light if an ionizing particle interacts inside it, deposting energy. The intensity of the light is

directly proportional to the energy deposited by the interacting particle with the ionization potential based

on the particle’s atomic number. The scintillator used is reported to be insensitive to photons withenergies over 100 keV as well as neutral particles. A thin film coating of rhodium (Rh), copper (Cu) or

palladium (Pd) on the scintillator functions as either an attenuator or a convertor to allow possible fusion

products to react with the scintillator, and also prevents the sonoluminescence light from generating false

readings. The nuclear properties of the scintillator and the coatings are given in table IV (refs. 34 and 35).

The relative response of the scintillator with coatings for each reaction was calculated using the

Monte Carlo program SRIM (ref. 36). For each coating (Rh, Cu, Pd) and ion (p, T, 3He, 4He), 10,000

input particles were used, and the balance of the energy of the particles transmitted through the coatings

was assumed deposited into the scintillator. The sum of the deposited energies were scaled based on the

reprted scintilator response to determine the light output.

For each fusion reaction scenario, the ouput of the detectors is normalized to the detector with the

largest signal. The results are shown in table V. Thus, comparing the response of each detector will allow

a reasonable identification of the reaction occuring in the cell. In this way, the fusion reactions that appear (or not) in sonoluminescent conditions can be determined, limited by the statistics of the actual counts and

background radiation.

The output for the D(d,n)³He reaction was determined from the helium-3 ion transport in SRIM, as

well as utilizing a 3-µm-thick rhodium film as a neutron convertor. Rhodium emits 2.44 MeV electrons in

the beta decay of caputured neutrons, and has an excellent thermal neutron absorption cross section of

145 barns/atom, which will capture about 0.1 percent of the neutron flux per micron thickness of film.

The emitted electron will be easily detectable as the scintillator sensitivity to electrons is reported to be

five times that for protons of equivalent energy.

Figure 17.—Schematic of thin film coated scintillating detector.

PMT Module

Fiber OpticConnector

WaveshiftingOptical Fiber

ScintillatingCube

Thin FilmCoating Power

Output

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NASA/TM—2007-214982 14

TABLE V.—RELATIVE SENSITIVITIES OF DETECTORS TO REACTIONS OF INTEREST

Detector film coating D(d,p)T D(d,n)3He D(d, γ)4He

Pd:D(d,p)T Pd:D(d,n)3He Pd:D(d, γ)4He

3.0 µm Rh 0.89 0.04

0.3 µm Cu 0.86 1.00 1.00

0.3 µm Pd 1.00 0.94 1.00 1.00 1.00

0.3 µm Pd/3.0 µm Rh 0.84 0.04 0.87 0.03

The use of palladium in ultrasonic systems as well as our observations in figures 13 and 14 suggests

that the metal should be considered in radiation detection. All three of the deuterium-deuterium reactions

will be tested with a palladium film included on the detectors as well as without. If palladium has a

catalytic role in fusion reactions, then the detectors with the palladium will be more sensitive as the

reactions are occurring inside the palladium film. The sensitivity was modeled in SRIM assuming thereactions occur at the bottom of the 0.3 µm Pd layer, based on the 0.375 µm radius globules seen in

figure 15, with all the particles deposited into the scintillator or rhodium.

The current assembly of the detectors is shown in figure 18. This assembly is too sensitive to

background counts to provide useful data at this time and improvements in the assembly are proceeding.

With modifications, the concept could potentially be used in other applications, such as radiation

monitoring at high altitudes or in space environments. This detector development effort was successfully

leveraged in radiation detector development for the application of dosimeters on surface suits for lunar

EVA (ref. 37).

Energy Harvesting Concept

The common goal of energy harvesting devices is to generate electricity from the environment. In thecase of energy harvesting from sonoluminescence, the environment has point locations of extremely hot

bubbles. The most direct method of energy harvesting of such localized heating is by thermoelectric

conversion to electricity.

Thermoelectric voltage generation uses the Seebeck effect, which is the generation of a potential

difference between two ends of a conductor or semiconductor that are at different temperatures. The

effect involves the movement of charge carriers from the hot end of the conductor, where the carrier

density is forced lower, to the cold end, where the carrier density is allowed to be greater. The electric

field due to the new distribution of charge carriers leads to a thermoelectric voltage. The voltage

(a) (b)

Figure 18.—Prototype thin film coated scintillating detector (a) assembly;(b) close-up of coated ¼-in. scintillator cube with a thin film of Pd.

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NASA/TM—2007-214982 15

generation per degree difference is referred to as the Seebeck coefficient. To complete the electrical

circuit a different conductor is used with its own Seebeck coefficient, making the net thermoelectric

voltage generated the difference of the two with a corresponding relative Seebeck coefficient. The

simplest example of this effect is a thermocouple used for temperature measurement (ref. 38).

If the thermoelectric voltage generated is high and the losses due to the thermal conduction and

electrical resistance of the conductors are low, then the voltage generated by such a device can be used to

generate power. This the form of power generation used on deep space probes (such as the Vikings,Voyagers and Galileo missions) where solar power, fuel cells and batteries are not practical. As their

name indicates, the heat source for radioisotope thermoelectric generators (RTG’s) on spacecraft is aradioactive pellet heating a ceramic block, and the cold side is the darkness of space.

To take advantage of the high temperature robustness of ceramics and the miniature non-intrusiveness

of thin films, GRC is investigating thin film ceramic thermocouples for high temperature environments.

Initial results revealed a chromium silicide film with a Seebeck coefficient to be similar to that of bulk

materials used thermoelectric generators (ref. 38). These results suggest that ceramic thin films can betailored for thermoelectric energy harvesting applications.

A schematic of the energy harvesting concept is shown in fig. 19. A 6-mm-diameter thermopile,

originally used for fabrication of heat flux sensors (shown in fig. 20), will be used in fabricating devices

for the initial test of a thermoelectric generator for sonoluminescence. The thermoelectric elements will

be made of high temperature ceramics, covered with electrical insulation for use in the liquid. The inner junction will be covered with a high temperature insulator embedded with a palladium catalyst based on

the indications of high temperature generation seen in figures 14 and 15.

The output of the generator can be estimated using the properties of the chromium silicide film

(ref. 38). A thermoelectric voltage of 200 mV per junction results assuming sonoluminescent bubbles

react on the inner junctions of the thermopile with a 2000 °C temperature difference from the surrounding

liquid. The thermopile resistance should be about 200 Ω per junction, giving 0.2 mW of power per

junction. About half of the generated power is expected be lost to the resistance of the thermopile. Thus, a

40-pair thermopile as shown in figure 20 should generate 4 mW of power under sonoluminescence. As

this 28 mm2 generator is a fraction of the MBSL area seen in figure 13, an array of generators can

conceivably output enough electrical power to match the acoustic power input to the system. Clearly, the

improvement of the Seebeck coefficient, thermal resistance or electrical conductivity is needed for the

high-performance thermoelectric generators needed to allow practical applications for energy harvestingof sonoluminescence.

Figure 20.—A 6-mm-diameter thermopile for initial test of ceramic thin-film thermoelectricdevice.

Figure 19.—Cross-section concept of a hightemperature thermopile for energy harvestingsonoluminescence.

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NASA/TM—2007-214982 16

Conclusions

Instrumentation techniques were explored at GRC to measure optical, radiation, and thermal

properties of the phenomena of sonoluminescence, the light generated using acoustic cavitation. The

objective of the effort was to investigate claims and theories of power generation based on

sonoluminescence, particularly from fusion reactions in the glowing bubbles. The approach was to

determine whether there is any difference in the emission from bubbles in light water and heavy water,then from bubbles in other solvents, eventually to formulate conclusions of sonoluminescence-based

power generation concepts utilizing the data from the experiments.

A resonating test cell and a Sonicator test cell were built to generate sonoluminescence. Multi-bubble

sonoluminescence in the tests cells were imaged with low-light cameras in a variety of containers.

Indications of high temperature generation were observed in palladium chromium films when exposed to

sonoluminescence in heavy water but not in light water. No indication of high temperature generation was

observed in platinum films exposed to sonoluminescence in heavy or light water, though the platinum

film is estimated to require about the same amount of energy to be modified as the palladium chromium

film.

Localized bright sonoluminescence was generated in glycerin saturated with water, allowing future

spectroscopic and other optical investigations. A design was presented for in situ radiation monitoring of

the sonoluminescence, with plans for future improvements. A concept for harvesting the effects seen inthis study as electricity was presented, however there is clear need for improving the thermoelectric

properties of the thin films for practical energy harvesting.

References

1. Putterman, S. J.: “Sonoluminescence: Sound into Light,” Scientific American, 32–37 (February 1995).

2. Frenzel, H.; and Schultes, H.: Z. Phys. Chem. B27, 421 (1934).

3. Gaitan, D.F.; Crum, L.A.; Church, C.C.; Roy, R.A.: “Sonoluminescence and bubble dynamics for a

single, stable, cavitation bubble,” J. Acoust. Soc. Am. 91, 3166–3183 (1992).

4. Moran, M.J.; Haigh, R.E.; Lowry, M.E.; Sweider, D.R.; Abel, G.R.; Carlson, J.T.; Lewia, S.D.;

Atchley, A.A.; Gaitan, D.F.; Maruyama, X.K.: “Direct observation of single sonoluminescence

pulses,” Nucl. Instr. and Meth. in Phys. Res. B 96 (3–4), 651–656 (May 1995).5. Hiller, R.; Putterman, S.J.; Barber, B.P.: “Spectrum of Synchronous Picosecond Sonoluminescence,”

Phys. Rev. Lett. 69 (8), 1182–1184 (August 1992).

6. Hiller, R.; Weninger, K.; Putterman, S.J.; Barber, B.P.: Science 266, 248 (1994).

7. Hiller, R.A.; and Putterman, S.J.: “Observation of Isotope Effects in Sonoluminescence,” Phys. Rev. Let. 75 (19), 3549–3551 (November 1995).

8. Didenko, Y.T.; McNamara, W.B.; Suslick, K.S.: “Temperature of multibubble sonoluminescence in

water,” J. Phys. Chem. 103 (50), 10783–10788 (December 1999).

9. Barber, B.P.; Wu, C.C.; Lofstedt, R.; Roberts, P.H.; Putterman, S.J.: “Sensitivity of

sonoluminescence to experimental parameters,” Phys. Rev. Lett. 72 (9), 1380–1383 (February 1994).

10. Prosperetti, A.: “A new mechanism for sonoluminescence,” J. Accoust. Soc. Am. 101, 2003–2007 (1997).

11. Prosperetti, A.: “Old-Fashioned Bubble Dynamics,” Sonochemistry and Sonoluminescence, L.A.

Crum et al. (eds.) (Kluwer, 1999), 159–164.12. Claudia Eberlein, “Sonoluminescence as Quantum Vacuum Radiation,” Phys. Rev. Let. 76 (20),

3842–3845 (May 1996).

13. Brodsky, A.M.; Burgess, L.W.; Robinson, A.L.: “Cooperative effects in sonoluminescence,” Physics Letters A 287, 409–414 (September 2001).

14. Schiffer, M.: “Sonoluminescence: The Superradiance Paradigm,” October 14, 1997,<http://arxiv.org/pdf/quant-ph/9710039> (October 2002).

15. Moss, W.C.; Clarke, D.B.; Young, D.A.: “Star in a Jar,” Sonochemistry and Sonoluminescence, L.A.

Crum et al. (eds.) (Kluwer, 1999), 159–164.

8/14/2019 Nasa/Tm—2007 214982


NASA/TM—2007-214982 17

16. Yasui, K.: “Effect of liquid temperature on sonoluminescence,” Phys. Rev. E 64 (June 2001).

17. Yasui, K.: “Temperature in multibubble sonoluminescence,” J. Chem. Phys. 115 (7), 2893–2896

(August 2001).

18. Margulis, M.A.; and Margulis, I.M.: “Contemporary review on nature of sonoluminescence and

sonochemical reactions,” Ultrasonics Sonochemistry 9, 1–10 (2002).

19. Matula, T.J.: “Single-bubble sonoluminescence in microgravity,” Ultrasonics 38 (2000) 559–565

20. Jorné, J.:“Ultrasonic Irradiation of Deuterium-Loaded Palladium particles suspended in HeavyWater,” Fus. Tech. 29, 83–90 (January 1996).

21. Moss, W.C.; Clarke, D.B.; White, J.W.; Young, D.A.: “Sonoluminescence and the prospects for table-top micro-thermonuclear fusion,” Physics Letters A 211 (2), 69–74 (February 1996).

22. Crum, L.A.: “Sonofusion: Star in a Jar?” Science Forum Colloquium Series, University of

Washington, November 21, 2003,

<http://www.washington.edu/research/scienceforum/pdfs/Crum.pdf> (December 2003).

23. Nomura, S.; and Toyota, H.:“Sonoplasma generated by a combination of ultrasonic waves andmicrowave irradiation,” Appl. Phys. Lett . 83 (22), 4503–4505 (December 2003).

24. Taleyarkhan, R.P.; West, C.D.; Cho, J.S.; Lahey Jr., R.T.; Nigmatulin, R.I.; Block, R.C.: “Evidence

for Nuclear Emissions During Acoustic Cavitation,” Science 295, 1868–1873 (March 2002).

25. Shapira D.; and Saltmarsh, M.: “Nuclear Fusion in Collapsing Bubbles—Is It There? An Attempt to

Repeat the Observation of Nuclear Emissions from Sonoluminescence,” Phys. Rev. Let. 89 (10)(September 2002).

26. Taleyarkhan, et al, “Additional Evidence of Nuclear Emission during Acoustic Cavitation”, Phys.

Rev. E 69 (2004).

27. Xu, Y.; and Butt, A.: “Confirmatory Experiments for Nuclear Emissions During Acoustic

Cavitation,” Nuc. Eng. Des. 235, (May 2005) 1317.

28. Forringer, E.R.; Robbins, D.; Martin, J.: “Confirmation of Neutron Production During Self-Nucleated

Acoustic Cavitation,” Transactions of the American Nuclear Society (November 2006) 736–7.

29. Lauterborn, W.; and Ohl, C.D.: “Acoustic Cavitation and Multi Bubble Sonoluminescence,”

Sonochemistry and Sonoluminescence, L.A. Crum et al. (eds.) (Kluwer, 1999), 97–104.

30. Hodgman, C.D.; et al. (eds.): Handbook of Chemistry and Physics (The Chemical Rubber Publishing

Co., Cleveland, 1960).

31. Young, F.R.: Sonoluminescence (CRC Press, Boca Raton, 2005).32. Hulse, C.O., Bailey, R.S.; Grant, H.P.; Anderson, W.L.; Przybyszewski, J.S.: “High Temperature

Static Strain Gauge Development,” NASA CR–189044 (NASA Lewis (Glenn) Research Center,

August 1991).

33. Kubaschewski, O., and Hopkins, B.E.: Oxidation of Metals and Alloys (Butterworths, London, 1967).

34. Berger, M.J.; Coursey, J.S.; Zucker, M.A.: “ESTAR, PSTAR, and ASTAR: Computer Programs for

Calculating Stopping-Power and Range Tables for Electrons, Protons, and Helium Ions (version

1.2.2)” (2000). [Online] URL: http://physics.nist.gov/Star [cited 15 September 2004]. National

Institute of Standards and Technology, Gaithersburg, MD. Originally published as: Berger, M.J.,

NISTIR 4999, National Institute of Standards and Technology, Gaithersburg, MD (1993).

35. Sears, V.F: “Neutron scattering lengths and cross sections,” Neutron News 3 (3) 26–37 (1992).

[Online] URL: http://www.ncnr.nist.gov/resources/n-lengths/list.html [cited 02 January 2004].

National Institute of Standards and Technology, Gaithersburg, MD.36. SRIM, The Stopping and Range of Ions in Matter, Software Package, Ver. 2003.26, Ziegler, J.F., and

Beirsack, J.P. (SRIM.org), Annapolis, MD, 2004.

37. Wrbanek, J.D.; Wrbanek, S.Y.; Fralick, G.C.; Chen, L.Y.: “Micro-fabricated Solid-State Radiation

Detectors for Active Personal Dosimetry,” NASA/TM—2007-214674 (February 2007).

38. Wrbanek, J.D.; Fralick, G.C.; Farmer, S.E.; Sayir, A.; Blaha, C.A.; Gonzalez, J.M.: “Development of

Thin Film Ceramic Thermocouples for High Temperature Environments,” 40th

AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit , Ft. Lauderdale, FL, July 11–14,

2004. NASA/TM—2004-213211 (August 2004).

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14. ABSTRACT

Instrumentation techniques are being developed at NASA Glenn Research Center to measure optical, radiation, and thermal properties of phenomena of sonoluminescence, the light generated using acoustic cavitation. Initial efforts have been directed to the generation of theeffect and the imaging of the glow in water and solvents. Several images have been produced of the effect showing the location withincontainers, without the additions of light enhancers to the liquid. Evidence of high energy generation in the modification of thin films fromsonoluminescence in heavy water was seen that was not seen in light water. Bright, localized sonoluminescence was generated usingglycerin for possible applications to energy harvesting. Issues to be resolved for an energy harvesting concept will be addressed.15. SUBJECT TERMS

Sonoluminescence; Cavitation flow; Solvents; Ultrasonic processing; Temperature effects

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